[Paroxysmal nocturnal dyspnea as a severe expression of the pacemaker syndrome]

Single-chamber ventricular pacing remains a frequent pacing method for symptomatic bradyarrhythmias. VVI pacing is effective in maintaining an acceptable ventricular rate, preventing severe bradycardia. However it may cause many important symptoms as a consequence of loss atrio-ventricular synchrony. Pacemaker syndrome (i.e. symptoms and signs caused by inadequate timing of atrial and ventricular contractions) may range in severity from vague pacing awareness to congestive heart failure. This event may be related more to retrograde ventricular-atrial conduction than to the absence of atrio-ventricular synchrony. We report 2 cases of VVI pacing complicated by nocturnal dyspnea (sign of congestive heart failure) as severe manifestation of pacemaker syndrome. By implantation of dual-chamber pacemaker, atrio-ventricular synchrony was restored, nocturnal dyspnea disappeared and has not recurred during clinical follow-up (12 and 4 months respectively for the first and second case.